In the redesign of the General Electric Recording Spectrophotometer many improvements have been made affecting its performance, versatility, and convenience. For example, new monochromator slit width ratios result in a twofold increase in light transmission, and other optical changes further increase the sensitivity. Among other improvements described are smaller size, faster speed of operation, and greater serviceability.
B. S. PRITCHARD and W. A. HOLMWOOD, "New Recording Spectrophotometer," J. Opt. Soc. Am. 45, 690-695 (1955)